In general, as is known, a display device includes a pair of substrates and a liquid crystal layer enclosed between the substrates. In a liquid crystal display device, liquid crystal molecules of a liquid crystal layer are driven by an electric field produced between pixel electrodes provided in respective pixels and a common electrode provided over a plurality of pixels, to thereby display an image.
The common electrode is made up of electrodes (hereinafter referred to as structural electrodes) associated with the pixels. There is a case where structural electrodes are isolated from each other by slits. For example, the slits each extend along an image signal line (source line) for supplying an image signal to a switching element connected to a pixel electrode.
Furthermore, because of provision of metal lines electrically connected to the common electrode, the resistance of the common electrode can be reduced. The metal lines are formed opposite to portions of a light-shielding layer which correspond to the boundaries between the pixels. For example, they are formed along image signal lines.
In a conventional liquid crystal display device, in order to avoid occurrence of a short-circuit in adjacent structural electrodes, metal lines do not cover slits. Therefore, the pixels are classified into pixels each of which satisfies a positional relationship in which metal lines are provided on both ends of a pixel, and pixels each of which satisfies a positional relationship in which a metal line is provided on only one of both ends of a pixel. For example, the aperture ratio of the above former pixels (each satisfying the positional relationship in which metal lines are provided on the both ends of a pixel) can differ from that of the above latter pixels (each satisfying the positional relationship in which a metal line is provided on only one the both ends of a pixel). Therefore, there is a possibility that the color displayed by the pixels will be shifted from a target color.
In such a manner, the quality of a displayed image can be reduced depends on the arrangement of metal lines. It is therefore necessary to prevent reduction of the quality of a displayed image, which depends on the arrangement of the metal lines.